Line a 15x10x1 inch baking sheet with parchment paper. Spray with baking spray (or grease and flour). Set aside. Sprinkle powdered sugar onto a large, clean dish towel (same size or bigger than baking sheet). Set aside.

In a large mixing bowl beat eggs for 2-3 minutes. Add sugar, water and vanilla and beat an additional minute until fully incorporated. Beat in flour, baking powder and salt. Pour into prepared baking sheet. Bake in a 375 degree F oven for 11-13 minutes.

Remove from oven and immediately flip cake onto powdered sugar towel. Peel off parchment paper. Place a clean sheet of parchment paper over back of cake and roll cake up in towel carefully (from short end to short end). Cool for one hour.

To make filling, beat heavy cream for several minutes until soft peaks form. Add in granulated sugar and vanilla and continue beating until desired consistency. Very gently, fold in sprinkles. Try not to over stir the sprinkles or the colors will start to bleed.

When cake is cooled, unroll gently. Remove parchment paper and spread filling in the cake. Re-roll the cake without the towel. Sprinkle with extra powdered sugar or sprinkles, if desired. Refrigerate cake on a plate with plastic wrap over the top. Serve and enjoy! This cake is best served within 1-2 days.